Eigenvector method for unstable resonator simulations

Eigenvector method is a numerical method for laser resonator with which all the eigenmodes and eigenvalues can be solved at the same time. This method is extended for unstable resonators combined with the Collins formula and the ABCD ray matrix in this paper. The mode behavior in a resonator with arbitrary irregular structures can be studied exactly and conveniently. An asymmetrical practical unstable resonator and a non-confocal practical unstable resonator are numerically simulated under varying structure parameters, and some new characteristics are found.